1. Field of the Invention
The present invention relates to starting systems for small internal combustion engines of the type used with lawnmowers, lawn tractors, snow throwers, generators, and other utility implements. In particular, the present invention relates to an electrical engine starting system that includes a starter motor powered by an external power source.
2. Description of the Related Art
Small internal combustion engines include starting systems which may be manually-actuated systems, such as manual recoil starters, or electrically-actuated systems which include a starter motor. Some small internal combustion engines may include both of the foregoing types of starting systems to allow operation of the engine where electrical power is either available or unavailable and/or to provide the operator with the option of either manual or electric starting.
Referring to FIGS. 1 and 2, an exemplary implement 20 is shown in the form of a snow thrower, which includes an engine 22 having a starting system 24 of the type shown in FIG. 2. Snow thrower 20 generally includes a frame or deck 26 to which engine 22 is mounted, and handle 28 extending from deck 26 which may be grasped by an operator to move snow thrower 20. Snow thrower 20 may optionally include a transmission (not shown) for driving wheels 30. Engine 22 drives an impeller mechanism (not shown) associated with an intake scoop 32 and a discharge chute 34 through which snow is discharged by the impeller mechanism.
Referring additionally to FIG. 2, engine 22 generally includes crankcase 36 to which one or more cylinders 38 are attached. A piston 40 in each cylinder drives crankshaft 42 which is rotatably supported by bearings within crankcase 36. Engine 22 additionally includes an intake system with a carburetor or a fuel injection device (not shown) supplied by fuel from a fuel tank (not shown), as well as an exhaust system (not shown) including a muffler and/or a catalytic converter (not shown). A flywheel 44 is secured for rotation on an end of crankshaft 42 which extends externally of crankcase 36, and may include a toothed ring gear that is engaged and rotated by the starting system 64 to crank crankshaft 42 for starting engine 22 in the manner described below.
Engine 22 may include a known, manually-operated recoil starter mechanism 46 associated with flywheel 44 and crankshaft 42, including a recoil starter handle attached to a rope of the recoil starter mechanism which may be pulled to engage the mechanism with flywheel 44 to manually rotate flywheel 44 and crankshaft 42 for starting engine 22.
Engine 22 also includes ignition circuit 48 which is operable during running of engine 22 to provide ignition pulses to spark plug(s) 50 of to initiate combustion within engine cylinder(s) 38. Typically, a permanent magnet 52 is fixed for rotation with flywheel 44 of engine crankshaft 42, and passes by a fixed magneto 54 during each crankshaft revolution to generate an electrical pulse that is conducted to spark plug 50 via lead 56 to fire spark plug 50 within the combustion chamber of engine cylinder 38. Many small internal combustion engines further include an engine shutdown or control switch 58, commonly referred to as a “kill” switch, which grounds ignition circuit 48 to terminate operation of engine 22. On some engines, engine control switch 58 may be coupled to a manually-actuable member, such as a bail assembly on the implement handle that is grasped by the operator for engine starting and running and is released by the operator for engine shutdown. On other engines, engine control switch 58 may be provided as a separate, manually-controlled switch that may be integrated with the throttle control device of the engine.
One known starting system for use with engine 22 having an ignition circuit 48 of the type described above includes a remote safety key 60 that is inserted into safety key switch 62 to enable ignition circuit 48. Ignition circuit 48 is grounded and disabled when safety key 60 is removed from safety key switch 62. Engine 22 additionally includes both a manually operable recoil starter 46 and an electric starter assembly 64 for starting the engine. The electric starter assembly 64 includes electric starter motor 66 having a pinion gear assembly for selective driving engagement with flywheel 44, and a separate start switch 68, such as a push-button switch, and also includes power connector 70 for connection to an external power source, such as a 110 volt AC wall outlet.
The safety key switch 62 and safety key 60 are included in all engines that include an electric starter assembly 64, such as that shown in FIGS. 1 and 2, and are also typically installed in all engines that could be equipped with an electric starter at some time after production, because the safety key switch 62 and safety key 60 are currently required when an electric starter assembly 64 is used on the engine.
In use, safety key 60 must first be inserted into safety key switch 62 for the ignition circuit 48 to be operable. Thereafter, either the manual recoil starter 46 or the electric starter assembly 64 is operated to start engine 22. When electrical starter assembly 64 is used, an electrical cord (not shown) from an external power source is plugged into power connector 70 of starter switch 68, and starter switch 68 is then actuated by the operator, such as via push button 72, to supply electrical power from the external power source to starter motor 66 to engage and crank flywheel 44 of crankshaft 42 for engine starting. After engine 22 starts, the operator releases button 72 of starter switch 68 and then disconnects the power cord from power connector 70. Thereafter, engine 22 is controlled by choke and throttle control assembly 74, which may include a lever actuator, for example.
Although the foregoing starting system has proven to be effective and reliable, the system includes a number of separate parts which must be assembled individually to engine 22 and must be connected to one another via several electrical leads. For example, safety key switch 62 is mounted to the engine housing as a separate component from choke and throttle control assembly 74 of the engine. Additionally, starter switch 68 and power connector 70 are separate from starter motor 66, and each must be separately mounted to engine 22. Furthermore, the safety key portion of the ignition circuit 48 shown in FIG. 2 usually requires extra wires external to the electric starter assembly portion of the circuit. Also, three separate switches are usually required in the configuration shown in FIGS. 1 and 2, including safety key switch 62, engine control switch 58, and a starter switch 68.
What is needed is a starting system for small internal combustion engines which is an improvement over the foregoing.